This invention pertains to battery contacts and, more particularly, to a battery contact assembly manufactured through the use of a solvent soluble plastic form.
The typical conventional battery contact is a coil spring, wherein one end of the spring is adapted to contact a battery terminal, while the other end of the spring is designed to connect to a circuit board. The connection between a battery terminal and the battery contact (i.e., the coil spring) is achieved by holding the battery terminal against the spring such that the spring is in compression. To connect the battery terminal to the circuit board, one end of the spring typically includes a soldering pin, or a surface mount soldering pad.
These conventional battery contacts are well suited for manual assembly. When placed in an automated assembly environment, however, these conventional battery contacts can cause serious problems. The first problem is entanglement. When a multiplicity of battery contacts are placed in the same container, the coil springs become entangled, making it difficult for automated assembly machinery to separate the entangled battery contacts. The second problem pertains to picking and placing. The coil spring is not the most suitable shape for a robot arm to pick up and precisely place onto a printed circuit board.
Accordingly, it would be desirable if the battery contact could be provided with a plastic housing that surrounds the spring to prevent entanglement. This housing should also include a flat, exterior surface to permit the use of a vacuum pickup arm to automatically pick and place the battery contact onto the printed circuit board.
Such a housing could be constructed by using conventional molding techniques to form a two-part housing that could be assembled around the battery contact. It would be more desirable, however, to have a one-piece injection molded housing that surrounds the battery contact and anchors one end of the battery contact within the molded housing. But, such an assembly cannot be manufactured with conventional injection molding techniques, because the spring must be molded within a cavity of the housing.
There is a well-known molding process known as the "lost wax" process which is suitable for cast molding cavities of the type described above. In this process, a wax form having the shape of the desired cavity is first prepared and placed into a mold. The housing material is then poured into the mold and around the wax form, and then cured. After curing, the wax is heated above its melting point, causing it to run out of the housing, thereby leaving a cavity behind. Although the lost wax process could be used to construct the form (i.e., the shape) of the invention described below, it would be desirable to use an injection molding process, which is incompatible with the lost wax process.
Accordingly, the invention described below is a battery contact assembly that is manufactured by a unique injection molding process that forms a one-piece housing that surrounds the battery contact and anchors one end of the contact into the housing.